1. Field of the Invention
The present invention relates to imaging plate guides and more particularly to imaging plate guides used in conjunction with a dental scanner.
2. Description of the Prior Art
In dental technology, intraoral x-ray images have traditionally been obtained by placing x-ray film in the patient""s oral cavity behind the tooth or teeth to be imaged. The film must be oriented correctly to optimize the region of the mouth that will be contained in the film""s image. In processing the film to make the latent image visible, films are processed either manually or by automatic film processors that use developer, fixer, wash and drying phases for the complete process. Since the images are contained within the film and are viewed by looking through the film, the angular orientation of the film within the processor is not critical except in some circumstances and perhaps for the reliability of the transporting of the film through the particular processors. The film is then viewed in either the portrait or landscape orientation as determined by the initial placement of film in the oral cavity, and for intraoral films, the films are typically placed into film holders for viewing.
Dental technology is now in the age of digital imaging. There are two basic types of digital imaging modalities, namely, CCD or CMOS based sensors (sometimes referred to as xe2x80x9clollipopsxe2x80x9d because the wire that protrudes from such a sensor is reminiscent of a lollipop stick) and the photo-stimulable phosphor (PSP) imaging plates. For the sensors which are direct reading, like film, the oral cavity orientation of the sensor is the only alignment requirement. However, for PSP imaging plates, although the latent image is contained within the imaging plate, much like film, the latent image has to be xe2x80x9creadxe2x80x9d opto-mechanically and the orientation of the imaging plate relative to the reading mechanism will determine how well the resulting images are oriented with respect to the portrait or landscape orientations, and therefore how well it is aligned with the digital holders within which the images are placed. If the reading line is inclined with respect to the axis of the imaging plate, then the rectangular image will appear skewed in the digital display device. Due to the nature of pixelized digital image data, de-skewing the image by computer rotation, requires two sets of coordinate transformations and/or interpolations, thereby losing image data and image resolution which is unacceptable. Also, most likely two sets of data would probably have to be stored, the original skewed data for legal data integrity reasons and an aligned display image for quick viewing, as reconstruction from the original skewed data to aligned display data is time consuming.
Therefore, the reader or scanner must read the plate in an aligned fashion. To accomplish this the image plates are placed either into holders or feed guides that orient them correctly with respect to the read lines. In batch process readers, a plate is automatically or manually placed into a frame that retains the imaging plate in the desired orientation. In continuous feed readers, provision has to be made to keep the plates aligned correctly while the plates are translated through the device and past the orthogonally or near orthogonally oriented read line. Typically, unique size holders for each plate size are required, intraoral and extraoral plates require holders that must be interchanged when going from one type to the other and the guides are either adjusted in their width or are exchanged for different widths. It is therefore desirable to develop imaging plate guides which permit the scanning of all sizes of intraoral image plates and allow scanning of extraoral image plates without having to remove the intraoral plate guides, yet allow interchange of intraoral plate guides when a different size plate is to be read.
An object of the present invention is to provide for imaging plate guides corresponding to the different sizes of dental intraoral film and extraoral imaging plates.
Another object of the present invention is to provide for imaging plate guides, which could be preloaded with imaging plates, and then inserted into their guide locations on the scanners.
A still further object of the present invention is to provide for novel imaging plate guides in which the guide slot is dimensioned to minimize skewing of the plate by no more than one half degree to one degree.
A still further object of the present invention is to provide for a novel imaging guide which is provided with a stop limiting means to allow the plate to be pushed only as far as necessary to engage the scanner transport mechanism.
A still further object of the present invention is to provide interchangeable intraoral plate guides that do not have to be removed to scan extraoral imaging plates.
An imaging plate guide formed in different configurations corresponding to the various intraoral dental plate sizes, which in turn correspond to the dental intraoral film sizes commonly referred to as sizes 0 through 4, the imaging plate guides dedicated to intraoral imaging providing for guides for each plate size so that a desired array of feed width guides can be positioned on the scanner for scanning the intraoral plates and which scan extraoral imaging plates as well. The embodiment of the imaging plate guides provides not only for interchangeability with respect to the intraoral plate size, but also allows for the feeding of extraoral imaging plates without the need to remove the intraoral plate guides. The size 4 is not specifically described, but is analogous to the other sizes as would be obvious to one skilled in the art.